MXPA96004049A - Molding process by blowing with stretching for the preparation of polipropil containers - Google Patents
Molding process by blowing with stretching for the preparation of polipropil containersInfo
- Publication number
- MXPA96004049A MXPA96004049A MXPA/A/1996/004049A MX9604049A MXPA96004049A MX PA96004049 A MXPA96004049 A MX PA96004049A MX 9604049 A MX9604049 A MX 9604049A MX PA96004049 A MXPA96004049 A MX PA96004049A
- Authority
- MX
- Mexico
- Prior art keywords
- crystalline propylene
- weight
- process according
- propylene copolymer
- copolymer
- Prior art date
Links
- 238000002360 preparation method Methods 0.000 title claims abstract description 6
- 238000000034 method Methods 0.000 title claims description 28
- 238000007664 blowing Methods 0.000 title claims description 13
- 238000000465 moulding Methods 0.000 title description 4
- 229920001577 copolymer Polymers 0.000 claims abstract description 29
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims abstract description 25
- -1 polypropylene Polymers 0.000 claims abstract description 15
- 239000004743 Polypropylene Substances 0.000 claims abstract description 14
- 229920001155 polypropylene Polymers 0.000 claims abstract description 14
- 238000000071 blow moulding Methods 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims abstract description 7
- VXNZUUAINFGPBY-UHFFFAOYSA-N ethyl ethylene Natural products CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 claims description 9
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 4
- 125000004432 carbon atom Chemical group C* 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims description 4
- 239000008096 xylene Substances 0.000 claims description 4
- 230000003750 conditioning effect Effects 0.000 claims description 3
- 238000002425 crystallisation Methods 0.000 claims description 3
- 230000008025 crystallization Effects 0.000 claims description 3
- 230000003287 optical effect Effects 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 2
- 239000002667 nucleating agent Substances 0.000 claims 3
- FMZUHGYZWYNSOA-VVBFYGJXSA-N (1r)-1-[(4r,4ar,8as)-2,6-diphenyl-4,4a,8,8a-tetrahydro-[1,3]dioxino[5,4-d][1,3]dioxin-4-yl]ethane-1,2-diol Chemical compound C([C@@H]1OC(O[C@@H]([C@@H]1O1)[C@H](O)CO)C=2C=CC=CC=2)OC1C1=CC=CC=C1 FMZUHGYZWYNSOA-VVBFYGJXSA-N 0.000 claims 2
- CHMCAIRITMOPFF-CGXNFDGLSA-N (3R,4S,5R,6S)-3-methyl-1,8-diphenylocta-1,7-diene-2,3,4,5,6,7-hexol Chemical compound C[C@@](C(O)=CC1=CC=CC=C1)(O)[C@@H](O)[C@H](O)[C@H](O)C(O)=CC1=CC=CC=C1 CHMCAIRITMOPFF-CGXNFDGLSA-N 0.000 claims 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 claims 2
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 claims 2
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 claims 2
- 229940087101 dibenzylidene sorbitol Drugs 0.000 claims 2
- 238000000113 differential scanning calorimetry Methods 0.000 claims 2
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 claims 2
- TVMXDCGIABBOFY-UHFFFAOYSA-N n-Octanol Natural products CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 claims 1
- 238000007669 thermal treatment Methods 0.000 claims 1
- 239000004711 α-olefin Substances 0.000 abstract 1
- 229920000642 polymer Polymers 0.000 description 7
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 229920000139 polyethylene terephthalate Polymers 0.000 description 5
- 239000005020 polyethylene terephthalate Substances 0.000 description 5
- YWEWWNPYDDHZDI-JJKKTNRVSA-N (1r)-1-[(4r,4ar,8as)-2,6-bis(3,4-dimethylphenyl)-4,4a,8,8a-tetrahydro-[1,3]dioxino[5,4-d][1,3]dioxin-4-yl]ethane-1,2-diol Chemical group C1=C(C)C(C)=CC=C1C1O[C@H]2[C@@H]([C@H](O)CO)OC(C=3C=C(C)C(C)=CC=3)O[C@H]2CO1 YWEWWNPYDDHZDI-JJKKTNRVSA-N 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 150000002978 peroxides Chemical class 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- 238000006116 polymerization reaction Methods 0.000 description 3
- 238000011946 reduction process Methods 0.000 description 3
- 239000000155 melt Substances 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 239000012815 thermoplastic material Substances 0.000 description 2
- DMWVYCCGCQPJEA-UHFFFAOYSA-N 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane Chemical compound CC(C)(C)OOC(C)(C)CCC(C)(C)OOC(C)(C)C DMWVYCCGCQPJEA-UHFFFAOYSA-N 0.000 description 1
- YKTNISGZEGZHIS-UHFFFAOYSA-N 2-$l^{1}-oxidanyloxy-2-methylpropane Chemical group CC(C)(C)O[O] YKTNISGZEGZHIS-UHFFFAOYSA-N 0.000 description 1
- XMNIXWIUMCBBBL-UHFFFAOYSA-N 2-(2-phenylpropan-2-ylperoxy)propan-2-ylbenzene Chemical compound C=1C=CC=CC=1C(C)(C)OOC(C)(C)C1=CC=CC=C1 XMNIXWIUMCBBBL-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000012967 coordination catalyst Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- LSXWFXONGKSEMY-UHFFFAOYSA-N di-tert-butyl peroxide Chemical compound CC(C)(C)OOC(C)(C)C LSXWFXONGKSEMY-UHFFFAOYSA-N 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229920001384 propylene homopolymer Polymers 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000000707 stereoselective effect Effects 0.000 description 1
- 125000000999 tert-butyl group Chemical group [H]C([H])([H])C(*)(C([H])([H])[H])C([H])([H])[H] 0.000 description 1
Abstract
The present invention relates to a stretch blow molding process for the preparation of polypropylene containers, wherein the use is made, as regards the polypropylene material, of a crystalline propylene copolymer containing from 4 to 12% by weight. weight of one or more alpha-olefins with 4 to 8 carbo atoms
Description
MOLDING PROCESS BY BLOWING WITH STRETCHING FOR THE PREPARATION OF POLYPROPYLENE CONTAINERS
CAIVPO OF THE INVENTION
The present invention relates to a stretch blow molding process for the preparation of polypropylene containers, particularly bottles.
BACKGROUND OF THE INVENTION
Stretch blow molding processes, both single-phase and two-phase, are commonly used in the art for the production of containers made of thermoplastic materials, particularly polyethylene terephthalate (PET). In fact, the PET tested is particularly suitable for use in the processes mentioned above since it allows itself to operate in a wide range of temperatures (processing window), and obtain molded products that have excellent mechanical properties and high transparency. However, due to its high cost, REF: 23099 there is a strong need to replace PET with alternative thermoplastic materials. In particular, crystalline propylene copolymers containing minor amounts of o-olefin comonomers (such as ethylene or 1-butene, for example) are known to have excellent mechanical properties, high transparency, and be less expensive than PET. On the other hand, the properties of said propylene copolymers are strongly influenced by the content of the crystalline polymer fraction, which is insoluble in xylene at 25 ° C, and by the dimensions and distribution of the crystals of said fraction in the mass of total polymer. Consequently, the physico-mechanical properties of the products obtained by the blowing process of crystalline propylene copolymers depend largely on the thermal history determined by the type of process and the specific conditions under which the latter is carried out. In the case of stress blow molding processes, which operate for example with crystalline propylene copolymers containing 1 to 3% by weight of ethylene, the window of processability during the blowing phase of the preforms is approximately + / - 2 ° C in terms of the temperature of said preforms, which are obtained by injection of the molten polymer in the appropriate molds. Variations greater than +/- 2 ° C during the aforementioned blowing phase cause a deterioration of the physico-mechanical properties as well as the homogeneity of the thickness of the finished product. This problem becomes particularly critical in the case of two-phase processes, wherein the preforms, obtained by injection of the polymer into the appropriate molds, are subjected to discontinuous blowing and stretching, and therefore, require a heating phase and thermal conditioning (at 130 ° C for example), which starts at room temperature (stretch blow molding with new heat treatment).
DESCRIPTION OF THE INVENTION
The Applicant has now developed a stretch blow molding process for the preparation of polypropylene containers wherein the use is made, as far as the polypropylene material, of a crystalline propylene copolymer containing from 4 to 12% by weight, preferably from 6 to 10% by weight, of one or more o-olefins with 4 to 8 carbon atoms. In particular, the process of the present invention comprises blowing a preform made of or comprising the aforementioned crystalline propylene copolymer. Generally said preform is obtained, as previously mentioned, by injection of the molten polymer in the appropriate molds. The crystalline propylene copolymer containing 4 to 12% by weight of one or more β-olefins with 4 to 8 carbon atoms, can be used in the pure state or in admixture with other olefin polymers, such as propylene homopolymers or crystalline propylene copolymers, containing 1 to 3% by weight of ethylene. The amount of said additional olefin polymers, when present, it is preferably from 10% to 40% by weight, most preferably from 10 to 30% by weight, based on the total weight of the polypropylene material. In the case of a two-phase process the Melt Flow Velocity of the crystalline propylene copolymer mentioned above, measured in accordance with ASTM D 1238 condition L (MFRL), preferably ranges from 6 to 20, most preferably from 8. at 12 g / 1 O min. In the case of a one-stage process, where the preform is extracted from the mold, it is immediately subjected to thermal conditioning, and blown without passing through a cooling phase at room temperature, the Melt Flow Rate L of the Crystalline propylene copolymer can be even lower, preferably greater than or equal to 1 g / 10 min. The use of the aforementioned crystalline propylene copolymer, which is the essential characteristic of the process of the present invention, allows to obtain finished products, in particular bottles and flasks, which have excellent physicomechanical properties, which operate with a window of processability of approximately +/- 4 ° C during the blowing phase. For example, blowing at 130 ° C may be required, a fluctuation in temperature in the preform from about 4 ° C to around that value (ie from 126 to 134 ° C) can be tolerated, since the fluctuations are basically they do not compromise the physical-mechanical properties and the homogeneity of the thickness in the finished product. Indicatively, the blowing temperature is dimethyldibenzylidene sorbitol (DMDBS) sold under the trademark Millad 3988. The crystalline propylene copolymers used in the process of the present invention are well known as such and belong to the family of the copolymers which can be obtained by means of the polymerization processes in the presence of coordination catalysts. Such processes and the copolymers obtained therefrom are widely described in the art. For example, the high yield and highly stereospecific Ziegler-Natta catalysts and polymerization processes described in European Patent No. 45977 can be used. The M.F.R.L. mentioned above can be obtained directly in polymerization by suitably adjusting the molecular weight regulating agent (such as hydrogen, for example), or it can be achieved by means of a viscosity reduction process at which the crystalline propylene copolymers are submitted. The process of reducing the viscosity of the polymer chains is carried out using the appropriate techniques. One of the techniques is based on the use of peroxides which are added to the copolymer in an amount that allows to obtain the desired degree of viscosity reduction. The peroxides which are more conveniently employed for the viscosity reduction process have a decomposition temperature which preferably varies from 150 to 250 ° C. Examples of said peroxides are di-tert-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (tert-butyl peroxy) hexin, and 2,5-dimethyl-2, 5-di (tert-butyl but-xi) hexane, which are sold under the tradename Luperox 101. The amount of peroxide required for the viscosity reduction process preferably ranges from 0.05% to 1% by weight of the copolymer. As previously stated, the process of the present invention allows to obtain polypropylene containers having superior physical-mechanical properties. For example, using a typical two-phase process, a propylene / 1-butene copolymer having the following properties: 1-butene content (% by weight): 8
MFRL (g / 10 min.): 10 fraction insoluble in xylene at 25 ° C (% by weight): 96.5 melting point (° C) 147 crystallization point (° C): 113 DMDBS content (% by weight) : 0.22 and under the following process conditions: PREFORM CHARACTERISTICS Weight of the preform (g) 30
Maximum thickness of preform (mm) 5
Preform weight (mm) 102
Maximum external diameter of preform (mm) 31.5 Minimum internal diameter of preform (mm) 21.5 PREFORMING MOLDING PARAMETERS Melting temperature of polymer (° C) 220
Molding temperature (° C) 20
Injection time (seconds) 6
Injection Pressure (MPa) 50 Total cycle time (seconds) 35
BLOWING PARAMETERS-STRETCHING OF THE BOTTLE Type of heating: infrared lamps with forced air circulation. Heating time (seconds): 90-120 Preform temperature ° C: 127 +/- 4 (measured with infrared television camera) Stretch and blow cycle time (seconds): 4.5 10
bottles obtained with the following characteristics: GEOMETRIC CHARACTERISTICS OF THE BOTTLE Weight of the bottle (g) 30 Average thickness of "." bottle (mm) 0. 37 +/- 0 .02 Bottle height (mm) 275 Cross section of square bottle with rounded corners
Diagonal of the cross section of the bottle (mm) 30 Transversal side of the bottle (mm) 65 Average radial stretch ratio: 2.3 Average axial stretch ratio: 3.2 Total stretch ratio 7.3 MECHANICAL CHARACTERISTICS OF THE BOTTLE DMTA radial to 23 ° C (MPa) 2320 Top load (N) 165 Optical clarity (%) 3.1 Note: Average radial stretch ratio = the ratio between the maximum internal diameter of the bottle and the maximum internal diameter of the preform before blowing; average axial stretch ratio = ratio 11
between the length measured in the bottle from the starting point of the stretch or axial tension to the inner bottom of the bottle, and the length measured from the corresponding point in the preform and the inner bottom of the preform; Total stretch ratio = relationship between the two relationships mentioned above; DMTA radial: measured according to ASTM D 5026 standard; Upper load: is the force of extraction by maximum pressure before the collapse (deformation) of the walls of the bottle; Optical clarity: measured according to the ASTM 1003 standard.
It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.
Having described the invention as above, the content of the following is claimed as property
Claims (9)
1. A stretch blow molding process for the preparation of polypropylene containers, characterized in that its use is made, as far as the polypropylene material, of a crystalline propylene copolymer containing from 4 to 12% by weight of one or more -olefins with 4 to 8 carbon atoms.
2. The process according to claim 1, characterized in that the polypropylene material is a crystalline propylene / 1-butene copolymer.
3. The process according to claim 1, characterized in that the crystalline propylene copolymer has a melting point ranging from 135 to 156 ° C, and a crystallization point ranging from 105 to 120 ° C.
4. The process according to claim 1, characterized in that the crystalline propylene copolymer has an in-soluble fraction content in xylene at 25 ° C greater than or equal to 93%. in weigh.
5. The process according to claim 1, characterized in that the polypropylene material comprises, in addition to the crystalline propylene copolymer, a nucleating agent in amounts ranging from 0.05 to 0.3% by weight.
6. The process according to claim 1, characterized in that the operation takes place in two phases using a crystalline propylene copolymer having a M.F.R.L. from 6 to 20 g / 10 min.
7. The process according to claim 1, characterized in that the operation takes place in a stage or stage and the preform is subjected to conditioning or thermal treatment and blowing without passing through a cooling stage or stage at room temperature, using a copolymer of crystalline propylene that has MFRL greater than or equal to 1 g / 10 min. from 125 to 1'35 ° C. The crystalline propylene copolymer used in the process of the present invention preferably has a melting point ranging from 135 to 156 ° C and a crystallization point ranging from 105 to 100 ° C. 120 ° C, both measured by DSC (Differential Scanning Calorimetry (Differential Scanning Calorimetry) with a temperature variation of 20 ° C per minute. In addition, the content of fraction insoluble in xylene at 25 ° C is preferably greater than or equal to 93% by weight, more preferably greater than or equal to 95% by weight. Specific examples of o-olefins with 4 to 8 carbon atoms contained in the crystalline propylene copolymer mentioned above are: 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene. Propylene / 1-butene copolymers are preferred. To obtain better transparency values (Optical clarity) It is also convenient to add a nucleating agent to the polypropylene material in amounts ranging from 0.05 to 0.3% by weight. Examples of nucleating agents are dibenzylidene sorbitol (DBS), methyldibenzylidene sorbitol (MDBS),
8. The use of the process according to claim 1, for preparing bottles and jars.
9. Polypropylene bottles and bottles obtained with the process of claim 1.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| MIMI95/A001931 | 1995-09-15 | ||
| IT95MI001931A IT1282942B1 (en) | 1995-09-15 | 1995-09-15 | STRETCH BLOW MOLDING PROCESS FOR THE PREPARATION OF POLYPROPYLENE CONTAINERS |
| MIMI95A001931 | 1995-09-15 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| MX9604049A MX9604049A (en) | 1997-07-31 |
| MXPA96004049A true MXPA96004049A (en) | 1997-12-01 |
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